Devices for indicating the condition of rest or movement of a rotatable shaft



Nov. 1, 1955 Filed March 4, 1954 J. EDELBLUT ET AL 2,722,680 DEVICES FOR INDICATING THE CONDITION OF REST OR MOVEMENT OF A ROTATABLE SHAFT 2 Sheets-Sheet 1 N V- 1955 J. EDELBLUT ET AL 2,722,630

DEVICES FOR INDICATING THE CONDITION OF REST OR MOVEMENT OF A ROTATABLE SHAFT Filed March 4, 1954 2 Sheets-Sheet 2 fly 2 United States Patent G DEVICES FOR INDICATING THE CONDITION OF REST R MOVEMENT OF A ROTATABLE SHAFT J ohann Edelblut and Giinther Ziegler, Frankfurt am Main, Germany Application March 4, 1954, Serial No. 414,068 Claims priority, application Germany March 10, 1953 14 Claims. (Cl. 340271) This invention relates to a device for indicating the condition of rest or movement of a rotatable shaft, for example on a motor vehicle. For such indication, hitherto, centrifugal switches or induction switches have usually been employed. Such switches, however, are useful primarily at the higher revolution speeds, and they are apt to be large constructionally and require comparatively large torques.

The present invention has for its object to provide for this purpose an indicating device of simple construction which will operate satisfactorily with small torque consumption and at slow revolution speeds.

In the indicating device-according to the invention two spring-loaded tappets are actuated alternately by a cam device driven by the shaft for operating electrical contacts controlling an indicator provided with an intermittent contact device, the arrangement being such that when the shaft is at rest the indicator gives an intermittent indication, whilst when the shaft is rotating the intermittent contact device is rendered inoperative.

Means are preferably provided for delaying the return of the contacts to their rest positions after. operation. For this purpose, each of the tappets may carry a piston which can slide freely in one direction but is retarded in the other direction. Alternatively, the delaying action may be effected by means of a diaphragm device having a spring-controlled non-return valve.

Figures 1 and 2 of the accompanying drawings respectively illustrate diagrammatically two alternative practical arrangements of indicating device according to the invention.

In the arrangement of Figure 1, the indicating device comprises a casing 1, through which passes the shaft 2 whose condition is to be indicated, a cam 3 being mounted on the shaft within the casing. The casing 1 has two cylindrical extensions 1a on opposite sides of the shaft 2, in which are respectively mounted two tappets 4 and 4a, carrying pistons 5 which slide in the cylindrical parts In of the casing 1. Each piston 5 carries a circumferential flexible strip similar to a cup-leather, whereby it can freely slide outwardly away from the shaft, whilst its inward movement is retarded by the pressure of the air in the casing. Springs 6 are provided for urging the pistons 5 inwardly to bring the inner ends of the tappets 4, 4a into engagement with the cam 3. The outer ends of the tappets 4 and 4a respectively operate contacts 7 and 7a, so that when the tappets are forced outwardly by the cam 3, these contacts will be closed.

When the shaft 2 is rotating in the direction of the arrow from the position shown, the earn 3 will first cause the tappet 4 to move outwards to close the contact 7 on the side A. On further rotation of the cam, the other tappet 4a will be operated to close the contact 7a on the side B, the tappet 4 being released by the cam. Owing to the delaying action of the piston 5, however, the tappet 4 will move inwards slowly under the action of the spring 6, so that the contact 7 on the side A will remain closed for a time, and the delaying action of the piston 5 is in fact so arranged that the contact 7 will still be closed when the cam 3 again moves the tappet 4 outwardly. Consequently, while the shaft 2 is rotating both contacts 7 and 7a remain closed, so that the connection between the leads 9 and 10 remains closed through these contacts and the lead 8 between them, and thus shortcircuits an intermittent contact device 11 of any suitable known type which is connected between the leads 9 and 10. The lead 9,is also connected through a hand-switch 13 and a lead 14 to one side of the battery 15, whilst the lead 10 is connected to the other side of the battery through leads 16 and 17 and through an indicating lamp 18. The shaft 2 may be one of the shafts in the driving mechanism of a motor vehicle and in such case the indicating lamp 18 can be arranged to constitute the tai light of the vehicle.

It will thus be clear that, while the shaft 2 is rotating, the one-sided cam 3 will cause the contacts 7 and 7a to remain continuously closed and to maintain the tail light or other indicating lamp 123 steadily alight, whilst when the shaft 2 is at rest, at least one of the contacts 7 and 7a will remain open and the lamp 18 will be energised through the intermittent contact device 11 and will flash in and out. The earn 3 is mounted on the shaft 2 through a free-wheel mechanism, so that it will rotate only when the shaft is driven in the forward direction and will re-, main stationary when the shaft is driven in the reverse direction, so that the intermittent flashing indication will be given by the lamp both when the shaft 2 is at rest and when it is rotating in the reverse direction.

It will be understood that the delaying action on the inward stroke of either tappet may be effected in other ways than by the piston 5, and that, if desired, further cams and tappets may be mounted on the shaft 2 for other purposes.

The arrangement so far described gives a simple flashing stop indication and a continuous running indication, but it will often be desirable to give an additional indication for use for example when a vehicle is standing at rest. The alternative arrangement shown in Figure 2 gives an example of this and includes means whereby the flashing stop indication can be cut off during long waits, for example, in towns.

Although various kinds of light indication are known for motor vehicles, a light indication, which is automatically switched on when the vehicle comes to rest and is automatically switched off when the vehicle starts again, has not hitherto been known. The arrangement of Figure 2 uses in addition to the automatic indication only an operation controlled by the brake lever and an operation by a hand knob.

The arrangement of Figure 2 differs from that of Figure 1 primarily in that four contacts are operated by the tappets instead of two, and that a hand knob is provided whereby the flashing stop indication can be cut out during long waiting but is automatically brought, when the vehicle starts again into a condition ready for operation on stopping.

In this arrangement the shaft 20 carries a cam 41 which controls two tappets 22 and 23 in the form of levers. The lever 22 acts in accordance with its position on two contacts 24 and 25, and the lever 23 similarly acts on two contacts 26 and 27.

The contact 24 is connected to earth through the lead 28 and the contact pair 26, 29. The contact 44, cooperating with the contact 24, is connected through the lead 30 to an electromagnet 31 and thence through a lead 32 to a contact 33, which in the position shown is engaged by a spring contact 34 connected to the battery B, the other side of the battery being earthed.

The contact 25 is connected through a lead 35 and through the contact pair 27, 36 to a lead 54, which is con- 3 nected through a lead 38 to a back-contact 39 which cooperates with the above-mentioned spring contact 34. The lead 35 is also connected through the lead 40 and through an intermittent contact device 51 to a pair of indicating stop lamps 53. The contact 37 which cooperates with the contact 25 is also connected to the lead 38, so that the two contact pairs 25, 37 and 27, 36 are in parallel with one another in the connection from the lead 38 to the flashing stop light indicating lead 40.

The lever 23 is controlled by a spring 42 tending to move the lever to close the contact pair 27, 36 and to open the contact pair 26, 29, whilst the rotation of the cam 41 causes this lever to close the contact pair 26, 29 and open the contact pair 27, 36. The lever 22 is acted on by a spring 43 tending to move the lever to close the contact pair 25, 37 and open the contact pair 24, 44, whilst the cam 41 causes this lever to close the pair 24, 44 and open the pair 25, 37. The return movement of the lever 22 under its spring action is delayed by means of a diaphragm device 47 provided with a spring-controlled non-return escape valve 58, this device acting on the lever through a rod 45. A similar diaphragm device 48 with a spring-controlled escape valve 59 acts through a rod 46 to delay the return movement of the lever 23 under its spring action.

The electromagnet 31 acts on a spring-controlled looking detent, which can engage in a notch in a switch rod 49 to hold the rod in its depressed position against the action of a return spring, when the rod has been depressed by a hand knob 50 to force the spring contact 34 into engagement with the contact 33. When the electromagnet is energised, it releases the lock and causes the switch rod 49 to spring back, and to allow the contact 34 to disengage from the contact 33 and engage the back-contact 39. The hand knob 50 is provided with a small lamp 56 connected through the lead 60 in parallel with the stop lamps 53.

Figure 2 shows the circuits in the positions occupied when the vehicle is standing at rest, the switch rod 49 being shown locked in its depressed position. This prepares at contacts 33, 34 the circuit to the electromagnet 31, but such circuit is broken at one or other of the series-connected contact pairs 24, 44 and 26, 29. Similarly, one or other of the parallel-connected contact pairs 25, 37 and 27, 36 must be closed, but the flashing stop light circuit is broken at contacts 35, 39. The supply from the battery B to these circuits is controlled by a light switch L, which is assumed to have been turned on.

On starting up the vehicle, the rotation of the cam 41 operates in turn the levers 22 and 23, and owing to the delaying action of the diaphragm devices 47 and 48, these levers remain in their operated positions, while the shaft 20 is rotating, and hold the two contact pairs 24, 44 and 26, 29 closed, thus completing the circuit from earth through these series-connected .con-

tact pairs to the electromagnet 31 and thence through the closed contacts 33, 34 to the battery B, so that the electromagnet 31 is energized to release the lock on the switch rod 49, which at once springs back and opens the contacts 34, 33, deenergising the electromagnet, and closes the contacts 34, 39 to prepare the flashing stop light circuit, which however remains broken, so long as the shaft 20 is rotating since the contact pairs 25, 37 and 27, 36 are then both open.

When the vehicle is slowed down by operation of the brake lever, a switch 55 controlled by the brake lever closes and completes a direct connection from the battery B to the stop lights 53, which therefore light up and remain steady so long as the brake lever is depressed. When the vehicle comes to rest and the brake lever is released, the stop lights 53 go out, but the flashing stop light circuit, after an interval of, say, or seconds dependent on the settings of the diaphragm devices, will be completed by the closing of at least one of the contact pairs 25, 37 and 27, 36, whereupon the lamps 53 will start flashing. As soon as the vehicle starts again, the flashing lights will be extinguished.

When travelling in towns, where relatively long halts may frequently occur owing to traflic congestion, the flashing light signal can be somewhat disturbing, and the arrangement of Figure 2 provides means whereby in such cases the flashing lights can be temporarily switched off, whilst still leaving them ready to come automatically into action when next they are required.

Thus, if in such circumstances the hand knob is depressed, it will lock itself in the depressed position, wherein it breaks the flashing light circuit by opening the contacts 34, 39 and at the same time prepares the electromagnet circuit at the contacts 34, 33. The flashing lights are therefore extinguished, but nothing further happens until the vehicle is again set in motion. When this takes place the cam 41 opens the flashing light contacts 25, 37 and 27, 36 and closes the contacts 24, 44 and 26, 29, thus completing the energising circuit to the electromagnet 31, which at once unlocks the switch rod 50 and thereby breaks the electromagnet circuit at contacts 34, 33 and closes the contacts 34, 39 in readiness for later energisation of the flashing light circuit. The flashing lights will thus come automatically into operation again, when the vehicle next comes to rest, in the manner already described.

It will be appreciated that the flashing of the lamps 53, when the vehicle is at rest, can at any time be converted into continuous steady burning of the lamps by depressing the brake lever and thus closing the switch 55. Thus, for example, when the vehicle is left standing at rest for a long period, the brake lever may be left locked in its depressed condition, thus giving a continuous steady light signal at the lamps 53.

It will be clear from the above description, that this arrangement provides for automatic operation, with additional voluntary controls, of the distinctive light signals required in all circumstances when travelling either inside or outside towns, and clearly indicates whether the vehicle is at rest or in motion.

The indicating device according to the invention can also be used on trailers. In this case, a flashing light on the trailer will operate in just the same way as on the vehicle itself, but it will be useful to provide an additional control, whereby on cutting off the electrical connection between the vehicle and the trailer, the flashing light indication on the trailer will automatically become operative. For this purpose, it is necessary to provide a battery on the trailer, as Well as on the vehicle, together with means for automatically switching such battery into operation when the main connection from the vehicle battery to the trailer is cut oif.

What we claim as our invention and desire to secure by Letters Patent is:

l. A device for indicating the condition of rest or movement of a rotatable shaft, comprising a cam device driven by the shaft, a pair of spring-loaded tappets actuated alternately by said cam device, electrical contacts controlled, respectively, by said tappets, an intermittent contact device connected with said contacts controlled by said tappets, and an indicator controlled by one of said contacts through said intermittent contact device so that when the shaft is at rest said indicator is actuated by one of said contacts and said intermittent contact device connected in series therewith so as to yield an intermittent indica- 4. An indicating device as claimed in claim 2, in which the delaying means includes a diaphragm device associated with each tappet, and a spring-controlled non-return valve for retarding the flow of air into such device.

5. An indicating device as claimed in claim 1, including a free-wheel mechanism between the cam device and the shaft, whereby the cam device is driven by the shaft only when the shaft is rotating in the forward direction.

6. A device for indicating the condition of rest or movement of a rotatable shaft, comprising a cam device driven by the shaft, two spring-loaded tappets actuated alternately by the cam device, an electrical contact pair associated with each tappet and closed thereby when the tappet is operated by the cam device, an intermittent contact device, means for connecting the two contact pairs in series in a short-circuiting connection across the intermittent contact device, an indicator, means for energising the indicator through the intermittent contact device whereby the indicator gives an intermittent indication when the shaft is at rest, whilst when the shaft is rotating the intermittent contact device is short-circuited and the indicator gives a continuous indication, means for delaying the opening of each contact pair When the associated tappet is released by the cam device, such means including a piston carried by the tappet, and means whereby the piston may slide freely in one direction but is retarded in the other direction.

7. A device for indicating the condition of rest or movement of a rotatable shaft, comprising a cam device driven by the shaft, a pair of spring-loaded tappets actuated alternately by the cam device, an electrical contact pair associated with each of said tappets and opened thereby when the tappets are operated by the cam device, an intermittent contact device connected with said contacts associated with said tappets, an indicator controlled by one of said contacts, and means whereby each of the two contact pairs controls an energising circuit for the indicator, said controlling means including the intermittent contact device so that when the shaft is at rest the indicator is actuated by one of said contacts and said intermittent contact device connected therewith so as to yield an intermittent indication whilst when the shaft is rotating the intermittent contact device is rendered inoperative, means for delaying the opening of each contact pair when the associated tappet is released by the cam device, such means including a piston carried by the tappet, and means whereby the piston may slide freely in one direction but is retarded in the other direction.

8. An indicating device as claimed in claim 7, and a self-locking switch operable, when the shaft is at rest, to interrupt the energising circuit to the indicator through the intermittent contact device.

9. An indicating device as claimed in claim 8, and an electromagnet for releasing the lock of the self-locking switch when the shaft is rotating, and thereby preparing the intermittent indication circuit ready for operation when the shaft next comes to rest.

10. An indicating device as claimed in claim 9, two additional contact pairs which are respectively closed by the two tappets when operated by rotation of the cam device, and means whereby such contact pairs are connected in series in an energising circuit for the electromagnet.

ll. An indicating device as claimed in claim 10, and a further contact in the energising circuit of the electromagnet, such contact being closed when the self-locking switch is operated and opened again when such switch is unlocked by the electromagnet.

12. An indicating device as claimed in claim 11, said self-locking switch having an indicating lamp connected in circuit with the main indicator.

13v An indicating device as claimed in claim 8, in which the self-locking switch incorporates an indicating lamp connected in circuit with the main indicator.

14. An indicating device as claimed in claim 8, for use on a motor vehicle, an additional switch operated by the brake lever of the vehicle, and means whereby such additional switch causes the indicator to give a continuous indication so long as the brake lever is operated.

References Cited in the file of this patent UNITED STATES PATENTS 2,592,342 Ryckman, Jr. Apr. 8, 1952 2,601,140 Hines June 17, 1952 2,666,870 Levy Jan. 19, 1954 2,678,430 Loescher May 11, 1954 

